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  1. #1
    Join Date
    Feb 2012
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    Part load conditions



    During part- load operation, the evaporator temperature rises and the condenser temperature
    falls, effectively increasing the COP. But at the same time, deviation from the design
    operation point and the fact that mechanical losses form a greater proportion of the total
    power negate the effect of improved COP, resulting in lower part- load efficiency.

    iread the above ^^^ in a book,the thing is i do not understand this.

    How would operating at part load increase the COP( change the evaporator and condensor temperature respectively)
    from what i noe of refrigeration:
    COP=te/tc-te
    where te= is the temperature of the refrigerant in the evaporator
    tc= the condensing temperature of the refrigerant

    By part load they mean when the refrigerator is not full( say with food in a domestic one)
    please explain ?
    thnks in advance



  2. #2
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    Re: Part load conditions

    Are you referring to Co-efficient of Performance (COP) ?


    COP can be expressed as

    COP = hh / hw (1)

    where
    COP = Coefficient of Performance
    hh = heat produced (Btu/h)
    hw = equivalent electric energy input (Btu/h) = 3413 Pw

    where
    Pw = electrical input energy (W)

    If a heat pump delivers 3 units of heat for every unit of energy input - the COP is 3.

    Example of COP on a Heat Pump

    Cooling Cycle: A heat pump delivering 60000 Btu/h with a total input of 9 kW:

    COP = (60,000 Btu/h / 3413) / 9 (kW)
    = 1.95

    Heating Cycle : A heat pump delivering 50000 Btu/h with a total input of 7 kW:

    COP = (50,000 Btu/h / 3413) 7 (kW)
    = 2.1

  3. #3
    Join Date
    Dec 2008
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    Re: Part load conditions

    1272_R.gifBalance Point

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